Inspired by a conflux of events: a post about demos in Mitch’s chemistry community, followed by a dangerous chemistry demo listed in About.com (below the jump), and ‘Things I won’t work with: FOOF’. I thought I’d mention a series of books near to my heart, full of exciting demos for any precocious high school student with an indulgent teacher or any teachers in the audience.
Bassam Shakhashiri’s Chemical Demonstrations : A Handbook for Teachers of Chemistry, along with vols. 2,3,4 are the absolute best demo books out there. Check them out on Google book’s preview, then buy, borrow, or steal them if you do demos.
However, there are provisos I would offer to a high school student. For example, when using cent pieces for their copper content … don’t. The newer (1981+) American cent coins have a zinc core. Just grab some copper wire from a hardware store … it’s quite cheap.
All of this brings us to my point … Bassam includes in the book (never intending it for unsupervised student use) the recipe for nitrogen triiodide.
… stop …
Look down at your hands. Pick your two least favorite fingers … now imagine them reduced to a chunky mist about 6 inches to the right of your body. If you make nitrogen triiodide without knowing what the hell you are doing that image will become reality. Ask one of its discoverers: Pierre Dulong ( who discovered NCl3, thanks for the kind note Ender!).
Many chemical demonstrations are dangerous, but, and this is a key point, their dangers are predictable. Metal cyanide compounds are dangerous: ingest them and you die, no saving throw. Add sulfuric acid to them in an enclosed space, you generate hydrogen cyanide gas, and you die, no saving throw. Leave a metal cyanide in a bottle on a bench, work with it in proper gear, and you live.
With nitrogen triiodide, you get no such guarantees. At any given moment, a puff of wind, a raised voice, a single stray ferrous ion drifting by, or even an alpha particle (if you can believe that) will set the damn material off. I’ve made the stuff six times, and the prep. is deceptively simple. Don’t, for the love of god, go the bleach route described some places … including YouTube. Ignore everything on YouTube about this compound, it’s not good for a prank; you try to paint this compound on a doorknob and you will lose a finger. People like About.com should be ashamed for putting up the synthesis without placing a warning prominently at the top, as I did, in very graphic terms.
I’m not a chemistry prude … I’m not! I think the thermite reaction is great fun, and certainly doable for a high school student, so long as you’re outdoors and 6 feet from anything flammable. Thermite is awesome to watch, easy to set up, and reasonably predictable. But, again, nitrogen triiodide is none of those. Let me leave you with a little story about the third time I made a batch.
My friend asked me to give a demo to his chemistry class. I had a class one room over, and he had an astronomy class to teach in the same room as the chemistry class, so I whipped up a batch of NI3 in his fume hood in the back of the room, spread it out to dry and tossed a blast shield around it for good measure. I went and did my classics lecture, and halfway through a particularly boring discussion of Seneca, I heard an enormous ‘boom’, followed by another loud crash. Running back to the darkened room, I found my friend with his hands over his face, shaking with laughter and the kids on the verge of tears. Apparently in the darkened, quiet astronomy class, the NI3 had not only detonated but also had knocked the blast shield down, flipping what was left of the NI3 out onto the floor. Every time someone moved until we had a chance to clean it up, ‘bang! bang!’. The blast shield was broken as well, though probably more from the fall … it was older than me.
Frankly, there are just easier things to work with.